Control device and control method for vacuum pump

ABSTRACT

The object of the disclosure is to prevent erroneous transition of an operation mode to an operation limitation mode. A control device 6 includes a controller 62. The controller 62 counts the number of times of occurrence of each of multiple types of abnormalities occurred in a vacuum pump 1, and issues a critical alarm in a case where the number of times of occurrence of each of the multiple types of abnormalities exceeds a predetermined threshold.

This application claims priority under 35 U.S.C. § 119 to Japanese Patent Applications No. 2022-31142 filed on Mar. 1, 2022. The entire disclosure of Japanese Patent Applications No. 2022-31142 is hereby incorporated herein by reference.

BACKGROUND OF THE INVENTION 1. Technical Field

The present disclosure relates to a vacuum pump control device and a vacuum pump control method.

2. Background Art

Some vacuum pumps discharge gas by rotating a rotor by a motor. In a vacuum pump described in JP-A-2004-150340, axial displacement of a rotor shaft is detected, the number of times of detection of the axial displacement is accumulated, and a warning is issued in a case where the cumulative number of times exceeds a predetermined number of times or exceeds a predetermined number of times within a predetermined time.

SUMMARY OF THE INVENTION

According to the vacuum pump described in JP-A-2004-150340, the warning is issued based only on the cumulative number of times of detection of the axial displacement of the rotor shaft, and other types of abnormalities are not taken into consideration. For this reason, in, e.g., a case where the cumulative number of times of detection of the axial displacement of the rotor shaft exceeds the predetermined number of times, but the number of times of occurrence of each of the other types of abnormalities is small, the warning is issued regardless of a low probability of the vacuum pump being broken down. That is, in the typical pump, there is a probability that the warning is issued even in a case where the warning does not need to be issued. Although not specifically limited, there is, for example, a probability that in a configuration in which the vacuum pump is stopped at the same time as issuance of the warning, the vacuum pump is stopped regardless of a low probability of the vacuum pump being broken down and operation of a device targeted for gas discharging by the vacuum pump is interfered. In a case where such a vacuum pump is applied to a semiconductor manufacturing device, unnecessary stop of the vacuum pump leads to a great problem such as stop of a manufacturing line.

The present disclosure has been made to solve the above-described typical problems, and an object thereof is to prevent erroneous issuance of a critical alarm according to the number of times of occurrence of only a single type of abnormality.

A control device according to one aspect of the present invention is a control device for a vacuum pump configured to discharge gas by rotating a rotor by a motor. The control device includes a controller. The controller is configured to count the number of times of occurrence of each of multiple types of abnormalities occurred in the vacuum pump, and issue a critical alarm in a case where the number of times of occurrence of each of the multiple types of abnormalities exceeds a predetermined threshold.

In the above-described control device, the critical alarm is issued when the number of times of occurrence of each of the multiple types of abnormalities occurred in the vacuum pump exceeds the predetermined threshold. That is, based on the number of times of occurrence of each of the multiple types of abnormalities, it is determined whether or not the critical alarm is to be issued. With this configuration, in a case where a probability of the vacuum pump being broken down is low because the number of times of occurrence of only a single type of abnormality is great and the number of times of occurrence of each of the other types of abnormalities is small, erroneous issuance of the critical alarm can be prevented. It should be noted that issuance of the critical alarm does not always require notification (e.g., a displayed sign or sound) to a user, and may include storage in a storage.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic showing the configuration of a vacuum pump;

FIG. 2 is a diagram showing the configuration of a control device;

FIG. 3 is a flowchart showing operation of the vacuum pump; and

FIG. 4 is a flowchart showing start-up operation of the vacuum pump.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS Entire Configuration of Vacuum Pump

A vacuum pump 1 will be described with reference to FIG. 1 . FIG. 1 is a schematic showing the configuration of the vacuum pump 1. The vacuum pump 1 includes a housing 2, a base 3, a rotor 4, a stator 5, and a control device 6.

The housing 2 includes a first end portion 11, a second end portion 12, and a first internal space SP1. A suction port 13 is provided at the first end portion 11. The first end portion 11 is attached to a gas-discharging target (not shown) . The first internal space SP1 communicates with the suction port 13. The second end portion 12 is positioned opposite to the first end portion 11 in an extending direction of the axis A1 of the rotor 4. The second end portion 12 is connected to the base 3. The base 3 includes a base end portion 14. The base end portion 14 is connected to the second end portion 12 of the housing 2.

The rotor 4 is connected to a shaft 21. The shaft 21 extends in the extending direction of the axis A1. The shaft 21 is rotatably housed in the base 3. The rotor 4 includes multiple stages of rotor blades 22 and a rotor cylindrical portion 23. The multiple stages of the rotor blades 22 are connected to the shaft 21. The multiple rotor blades 22 are arranged at intervals in the extending direction of the axis A1. Although not shown in the figure, the multiple stages of the rotor blades 22 radially extend about the shaft 21. It should be noted that, in the drawing, a reference numeral is assigned only to one of the multiple stages of the rotor blades 22 and reference numerals for the other rotor blades 22 are omitted. The rotor cylindrical portion 23 is arranged below the multiple stages of the rotor blades 22. The rotor cylindrical portion 23 extends in the extending direction of the axis A1.

The stator 5 includes multiple stages of stator blades 31 and a stator cylindrical portion 32. The multiple stages of the stator blades 31 are connected to an inner surface of the housing 2. The multiple stages of the stator blades 31 are arranged at intervals in the extending direction of the axis A1. Each of the multiple stages of the stator blades 31 is arranged between adjacent ones of the multiple stages of the rotor blades 22. Although not shown in the figure, the multiple stages of the stator blades 31 radially extend about the shaft 21. It should be noted that, in the drawing, a reference numeral is assigned only to two of the multiple stages of the stator blades 31 and reference numerals for the other stator blades 31 are omitted. The stator cylindrical portion 32 is fixed in thermal contact with the base 3. The stator cylindrical portion 32 is arranged so as to face the rotor cylindrical portion 23 with a slight clearance in a radial direction of the rotor cylindrical portion 23. A spiral groove is provided at an inner peripheral surface of the stator cylindrical portion 32.

As shown in FIG. 1 , a second internal space SP2 is formed further on a downstream side of gas-discharging-downstream-side end portions of the rotor cylindrical portion 23 and the stator cylindrical portion 32. Gas discharged from the gas-discharging target is discharged into the second internal space SP2. The second internal space SP2 communicates with an exhaust port 16. The exhaust port 16 is provided at the base 3. Another vacuum pump (not shown) is connected to the exhaust port 16.

The control device 6 is housed in a case 33 provided below the base 3 to control the vacuum pump 1. Moreover, the control device 6 issues an alarm or a warning to notify occurrence of an abnormality in the vacuum pump 1 in a case where a levitation position of the shaft 21 measured by later-described displacement sensors 44A to 44C, a value of current supplied to a motor 42 and measured by a current value measurement device, and the number of rotations of the rotor 4 measured by a rotation number sensor 43 are not within normal value ranges. The control device 6 is a computer system including a CPU, a storage device such as a ROM, various interfaces and the like.

An operation device 7 is connected to the control device 6. The operation device 7 is a device for inputting various types of information regarding control of the vacuum pump 1. The operation device 7 may include a display for displaying various types of information regarding the vacuum pump 1. The operation device 7 is, for example, an operation board including an input device and the display. The input device is, for example, a device including a keyboard, a button or the like and/or a device capable of inputting various types of information by operation of, e.g., a touch panel by a user. As other alternatives, the operation device 7 may be a terminal such as a personal computer, a tablet terminal, or a mobile terminal.

The vacuum pump 1 includes multiple bearings 41A to 41E, the motor 42, and the rotation number sensor 43. The multiple bearings 41A to 41E are attached to positions at which the shaft 21 is housed in the base 3. The multiple bearings 41A to 41E rotatably support the rotor 4. The bearings 41A, 41E are, for example, ball bearings. On the other hand, the other bearings 41B to 41D are magnetic bearings. The bearings 41B to 41D as the magnetic bearings each include bearing electromagnets and the displacement sensors 44A to 44C (FIG. 2 ), and, e.g., the levitation position of the shaft 21 is detected by the displacement sensors 44A to 44C.

The motor 42 rotatably drives the rotor 4. The motor 42 includes a motor rotor 42A and a motor stator 42B. The motor rotor 42A is attached to the shaft 21. The motor stator 42B is attached to the base 3. The motor stator 42B is arranged so as to face the motor rotor 42A. A motor current measurement device 45 (FIG. 2 ) configured to measure a value of current supplied to the motor 42 is connected to the motor 42. The rotation number sensor 43 measures the number of rotations of the shaft 21 (i.e., the rotor 4).

A heater 51 and a not-shown coolant pipe that control the temperature of the base 3 are provided on an outer wall of the base 3. The temperature of the base 3 is detected by a temperature sensor 52. Based on the temperature detected by the temperature sensor 52, the temperature of the base 3 is controlled according to balance between heating of the base 3 by the heater 51 and cooling of the base 3 by coolant flowing in the coolant pipe. A heater current measurement device 53 (FIG. 2 ) configured to measure a current supplied to the heater 51 is connected to the heater 51.

In the vacuum pump 1, the multiple stages of the rotor blades 22 and the multiple stages of the stator blades 31 form a turbo-molecular pump portion. The rotor cylindrical portion 23 and the stator cylindrical portion 32 form a screw groove pump portion. In the vacuum pump 1, the rotor 4 is rotated by the motor 42, and accordingly, gas flows into the first internal space SP1 through the suction port 13. The gas in the first internal space SP1 passes through the turbo-molecular pump portion and the screw groove pump portion, and then, is discharged into the second internal space SP2. The gas in the second internal space SP2 is discharged through the exhaust port 16. As a result, the inside of the attachment target attached to the suction port 13 is brought into a high vacuum state.

Configuration of Control Device

The configuration of the control device 6 will be described with reference to FIG. 2 . FIG. 2 is a diagram showing the configuration of the control device 6. The control device 6 has a storage 61 and a controller 62. The storage 61 is part or the entirety of a storage area provided in a storage device forming the control device 6. The storage 61 stores various parameters regarding the vacuum pump 1, a program that controls the vacuum pump 1 and the like. Specifically, the storage 61 stores an abnormality occurrence condition CON, a critical alarm condition RCO, a critical alarm issuance history AH, and a cancellation password PW. The abnormality occurrence condition CON includes a condition for determining that the abnormality has occurred in the vacuum pump 1.

Specifically, the abnormality occurrence condition CON defines occurrence of an abnormality in the number of rotations of the rotor 4 when the number of rotations of the rotor 4 measured by the rotation number sensor 43 reaches a predetermined rotation number or less. Such an abnormality in the number of rotations is an abnormality regarding the load of the vacuum pump 1, and indicates that the vacuum pump 1 is in an overload state. The “overload state” means a state in which the torque of the motor 42 necessary for rotating the rotor 4 to a set number of rotations is excessively greater than that in a normal state. The vacuum pump 1 in the overload state indicates, for example, a state in which many products are accumulated in the vacuum pump 1. If this state continues for a long period of time, there is a probability that damage of the rotor blades 22 occurs due to contact of the accumulated products with the rotor blades 22 of the vacuum pump 1.

The abnormality occurrence condition CON defines occurrence of an abnormality in the position of the shaft 21 (the rotor 4) when the position of the shaft 21 measured by the displacement sensors 44A to 44C fluctuates with a predetermined fluctuating range or more or the position of the shaft 21 is shifted from the axis A1 within a predetermined range. The abnormality in the position of the shaft 21 is an abnormality regarding vibration of the vacuum pump 1, and means a state in which the vacuum pump 1 is vibrating. In a case where the vacuum pump 1 is vibrating, there is a probability that the rotor blades 22 of the vacuum pump 1 contact other components (e.g., the stator blades 31), for example. As a result, when the vacuum pump 1 is vibrating, there is a probability that the rotor blades 22 (and the stator blades 31) are damaged. Vibration of the vacuum pump 1 might indicate a state in which many products are accumulated in the rotor 4 of the vacuum pump 1. This is because of off-balance of the rotor 4 due to product accumulation.

The abnormality occurrence condition CON defines occurrence of an abnormality in the current value of the motor 42 when the current value of the motor 42 measured by the motor current measurement device 45 reaches a predetermined value or more. Such an abnormality in the current of the motor 42 indicates that the motor 42 operates with an excessive torque generated. That is, the abnormality in the current of the motor 42 is an abnormality regarding the load of the vacuum pump 1, and indicates that the vacuum pump 1 is in the overload state. The vacuum pump 1 in the overload state indicates, for example, a state in which many products are accumulated in the vacuum pump 1.

The abnormality occurrence condition CON defines occurrence of an abnormality regarding the temperature of the vacuum pump 1 when the temperature of the base 3 measured by the temperature sensor 52 is a predetermined temperature or less and/or the current value of the heater 51 measured by the heater current measurement device 53 is a predetermined value or less. The abnormality regarding the temperature of the vacuum pump 1 indicates a state in which the temperature of the vacuum pump 1 is not properly adjusted. If the temperature of the vacuum pump 1 is not properly adjusted, there is a probability that products are accumulated in the vacuum pump 1 and the rotor blades 22 are damaged due to contact of these products with the rotor blades 22. The abnormality regarding the temperature often occurs due to disconnection of the heater 51 or breakdown of the temperature sensor 52, for example. When the temperature of the vacuum pump 1 reaches the predetermined value or more, a power supply to the heater 51 is stopped by a thermal switch (not shown).

An abnormality occurrence counter CNT is information indicating the number of times of occurrence of each of the above-described abnormalities. Specifically, the abnormality occurrence counter CNT indicates the number of times of occurrence of each of the above-described multiple types of abnormalities (the abnormality regarding the load, the abnormality regarding the temperature, and the abnormality regarding the vibration).

The critical alarm condition RCO includes a condition for issuing an alarm (referred to as a critical alarm) for causing an operation mode of the vacuum pump 1 to transition to an operation limitation mode. The operation limitation mode indicates an operation mode in which operation of the vacuum pump is limited as compared to normal operation when the vacuum pump 1 is restarted after the vacuum pump 1 has been stopped due to issuance of the critical alarm. The critical alarm condition RCO includes the number of times of occurrence of each of the above-described multiple types of abnormalities for issuing the critical alarm. Specifically, the critical alarm condition RCO defines issuance of the critical alarm when the abnormality regarding the vibration has occurred a first threshold or more, the abnormality regarding the load has occurred a second threshold or more, and the abnormality regarding the temperature has occurred a third threshold or more, for example.

Using the operation device 7, the user can change the above-described first to third thresholds included in the critical alarm condition RCO, as necessary. The user can also select, using the operation device 7, two or more types of abnormalities included in the critical alarm condition RCO from the multiple types (three types) of abnormalities (the abnormality regarding the load, the abnormality regarding the temperature, and the abnormality regarding the vibration), as necessary. Thus, a critical alarm issuance condition can be set optimally according to use environment of the vacuum pump 1.

The critical alarm issuance history AH is information indicating whether or not the critical alarm has been issued. The critical alarm issuance history AH may be, for example, flag information indicating a value of “1” in a case where the critical alarm has been issued and a value of “0” in a case where no critical alarm has been issued. The cancellation password PW is a password for cancelling the issued critical alarm.

The controller 62 is a hardware including the CPU and various interfaces forming the control device 6, and executes control of the vacuum pump 1. The controller 62 implements functions regarding control of the vacuum pump 1 by executing programs stored in the storage 61. Some functions may be implemented by the hardware included in the controller 62.

Operation of Vacuum Pump

Hereinafter, operation of the vacuum pump 1 will be described with reference to FIG. 3 . FIG. 3 is a flowchart showing operation of the vacuum pump 1. Operation of the vacuum pump 1 as shown in FIG. 3 is operation in a case where no critical alarm has been issued before start-up of the vacuum pump 1 and the operation mode of the vacuum pump 1 is not the operation limitation mode. Such operation is executed by the control device 6 of the vacuum pump 1.

When the vacuum pump 1 is started up and operation thereof is started accordingly, the controller 62 acquires, during operation of the vacuum pump 1, each of the number of rotations of the rotor 4 measured by the rotation number sensor 43, the position of the shaft 21 measured by the displacement sensors 44A to 44C, the current value of the motor 42 measured by the motor current measurement device 45, the temperature of the base 3 measured by the temperature sensor 52, and the current value of the heater 51 measured by the heater current measurement device 53 (Step S1).

Next, the controller determines whether or not the number of rotations of the rotor 4, the position of the shaft 21, the current value of the motor 42, the temperature of the base 3, and the current value of the heater 51 acquired in Step S1 match the abnormality occurrence conditions indicated by the abnormality occurrence condition CON. For example, the controller 62 compares these measurement values with each threshold indicated by the abnormality occurrence condition CON (Step S2).

As a result of comparison above, in a case where any of the above-described sensor measurement values matches the abnormality occurrence condition indicated by the abnormality occurrence condition CON, such as a case where any of the above-described sensor measurement values exceeds the threshold (“Yes” in Step S2), the controller 62 determines that the type of abnormality (the abnormality regarding the vibration of the vacuum pump 1, the abnormality regarding the number of rotations of the rotor 4, or the abnormality regarding the temperature of the vacuum pump 1) corresponding to the item (the number of rotations of the rotor 4, the position of the shaft 21, the current value of the motor 42, the temperature of the base 3, or the current value of the heater 51) indicating the measurement value matching the abnormality occurrence condition has occurred (Step S3). It should be noted that, when it is determined that the abnormality has occurred, the controller 62 may notify occurrence of the abnormality by making sound or displaying a sign of abnormality occurrence on the display of the operation device 7, for example.

On the other hand, in a case where any of the above-described sensor measurement values does not match, as a result of comparison above, the abnormality occurrence condition indicated by the abnormality occurrence condition CON (“No” in Step S2), operation of the vacuum pump 1 returns to Step S1. That is, the controller 62 determines that no abnormality has occurred in the vacuum pump 1, and continues operation of the vacuum pump 1.

In a case where it is, in Step S3, determined that the abnormality has occurred, the controller 62 increases, in the abnormality occurrence counter CNT, the number of times of occurrence of the type of abnormality determined as occurred in Step S3 by one (Step S4).

Thereafter, the controller 62 compares the abnormality occurrence counter CNT and the critical alarm condition RCO with each other, and determines whether or not the number of times of occurrence of each of the multiple types of abnormalities indicated by the abnormality occurrence counter CNT matches the critical alarm issuance condition indicated by the critical alarm condition RCO (Step S5). Specifically, when the abnormality occurrence counter CNT shows, for example, that the number of times of occurrence of the abnormality regarding the vibration is the first threshold or more, the number of times of occurrence of the abnormality regarding the load is the second threshold or more, and the number of times of occurrence of the abnormality regarding the temperature is the third threshold or more, the controller 62 determines that the number of times of occurrence of each of the multiple types of abnormalities matches the critical alarm issuance condition indicated by the critical alarm condition RCO.

In a case where the number of times of occurrence of each of the multiple types of abnormalities matches the critical alarm issuance condition (“Yes” in Step S5), the controller 62 determines that the critical alarm has been issued (Step S6) . It should be noted that, when it is, in Step S6, determined that the critical alarm has been issued, the controller 62 may notify issuance of the critical alarm by making sound or displaying a sign of critical alarm issuance on the display of the operation device 7, for example.

When it is determined that the critical alarm has been issued, the controller 62 records issuance of the critical alarm in the storage 61 (Step S7). Specifically, the controller 62 records issuance of the critical alarm in the critical alarm issuance history AH stored in the storage 61. More specifically, the controller 62 records, for example, a value of “1” in the critical alarm issuance history AH to record a critical alarm issuance flag of “ON”.

Thereafter, the controller 62 stops the vacuum pump 1 as protective operation (Step S8). It should be noted that the information recorded in the critical alarm issuance history AH is not reset even after the vacuum pump 1 has been stopped and the vacuum pump 1 (the control device 6) has been powered off. That is, the critical alarm issuance history AH is stored in a storage area of the storage 61 where the information can be held even after a power supply to the control device 6 has been cut off (e.g., a storage area of a non-volatile memory such as an HDD, an SSD, an EEPROM).

By executing Steps S1 to S8 described above, the controller 62 can determine that the critical alarm has been issued when not only the number of times of occurrence of a single type of abnormality but also the number of times of occurrence of each of the multiple types of abnormalities exceeds the predetermined thresholds. As a result, in a case where a probability of the vacuum pump 1 being broken down is low because the number of times of occurrence of only a single type of abnormality is large and the number of times of occurrence of each of the other types of abnormalities is small, erroneous issuance of the critical alarm can be prevented.

Since the critical alarm is issued when the number of times of occurrence of each of the multiple types of abnormalities exceeds the predetermined threshold, such a critical alarm can prompt the user to repair and/or replace the vacuum pump 1. For example, each of the abnormality regarding the vibration of the vacuum pump 1, the abnormality regarding the number of rotations of the rotor 4, and the abnormality regarding the temperature of the vacuum pump 1 has a relationship with product accumulation. Thus, in a case where the critical alarm has been issued, it can be assumed that product accumulation is excessive, and overhaul for removing the products is prompted.

Start-Up Operation of Vacuum Pump

Next, start-up operation of the vacuum pump 1 will be described with reference to FIG. 4 . FIG. 4 is a flowchart showing the start-up operation of the vacuum pump 1. When the vacuum pump 1 is powered on and start-up thereof is started, the controller 62 determines whether or not the critical alarm issuance history AH stored in the storage 61 indicates that the critical alarm has been issued before this start-up (Step S11) . Specifically, the controller 62 determines, for example, whether or not the value of the critical alarm issuance history AH is “1” and the critical alarm issuance flag is “ON.”

In a case where the critical alarm issuance history AH does not indicate issuance of the critical alarm (“No” in Step S11), the controller 62 causes the vacuum pump 1 to operate in a normal operation mode (Step S12). That is, the controller 62 executes Steps S1 to S8 described above.

On the other hand, in a case where the critical alarm issuance history AH indicates issuance of the critical alarm (“Yes” in Step S11), the controller 62 determines that the operation mode of the vacuum pump 1 is the operation limitation mode, and causes the vacuum pump 1 to operate in the operation limitation mode.

Specifically, the controller 62 first causes the vacuum pump 1 to operate only for a predetermined time after the start-up (Step S13). For example, in a case where the gas-discharging target for which the vacuum pump 1 performs vacuum pumping is a chamber used for a semiconductor manufacturing process, the controller 62 causes the vacuum pump 1 to operate for a time for which the semiconductor manufacturing process can be performed a predetermined number of times after the start-up, for example. The controller 62 causes the vacuum pump 1 to operate only for two hours after the start-up, for example.

After the vacuum pump 1 has operated only for the predetermined time after the start-up, the controller 62 stops the vacuum pump 1 (Step S14).

Since Steps S11 to S14 described above are executed at the time of starting up the vacuum pump 1 as described above, the controller 62 causes the operation mode of the vacuum pump 1 to transition to the operation limitation mode in which operation is limited in a case where the critical alarm has been issued before the start-up of the vacuum pump 1, and therefore, can prevent breakdown of the vacuum pump 1 due to the normal operation thereof. Moreover, since the vacuum pump 1 operates only for the predetermined time in the operation limitation mode, the vacuum pump 1 can be used only for the predetermined time while an operation state of the vacuum pump 1 is checked.

Critical Alarm Cancellation Method

Hereinafter, a method for cancelling the critical alarm after the vacuum pump 1 has been repaired and/or replaced due to issuance of the critical alarm will be described. The critical alarm can be cancelled in such a manner that the user inputs a dedicated password via the operation device 7.

Specifically, when the password is input via the operation device 7, the controller 62 compares the input password with the cancellation password PW stored in the storage 61. As a result of such comparison, when the input password and the cancellation password PW are coincident with each other, the controller 62 records non-issuance of the critical alarm in the critical alarm issuance history AH. Specifically, the controller 62 changes the value of the critical alarm issuance history AH from “1” to “0,” to change the critical alarm issuance flag to “OFF,” for example.

Since the critical alarm is cancelled using the dedicated password as described above, free cancellation of the critical alarm can be prevented. As a result, unnecessary operation of the vacuum pump 1 when a probability of the vacuum pump 1 being broken down is high can be prevented.

One embodiment of the present invention has been described above, but the present invention is not limited to the above-described embodiment and various changes can be made without departing from the gist of the present invention.

The way to limit operation of the vacuum pump 1 in the operation limitation mode is not limited to operation of the vacuum pump 1 available only for the predetermined time, and can be set as necessary according to, e.g., use environment of the vacuum pump 1.

In the vacuum pump 1 according to the above-described embodiment, the turbo-molecular pump portion may be omitted. That is, the vacuum pump 1 may be a screw groove pump.

Those skilled in the art understand that the above-described multiple exemplary embodiments are specific examples of the following aspects.

(First Aspect) A control device is a control device for a vacuum pump configured to discharge gas by rotating a rotor by a motor. The control device includes a controller. The controller is configured to count the number of times of occurrence of each of multiple types of abnormalities occurred in the vacuum pump, and issue a critical alarm in a case where the number of times of occurrence of each of the multiple types of abnormalities exceeds a predetermined threshold.

In the control device according to the first aspect, the critical alarm is issued when the number of times of occurrence of each of the multiple types of abnormalities occurred in the vacuum pump exceeds the predetermined threshold. That is, based on the number of times of occurrence of each of the multiple types of abnormalities, it is determined whether or not the critical alarm is to be issued. With this configuration, in a case where a probability of the vacuum pump being broken down is low because the number of times of occurrence of only a single type of abnormality is great and the number of times of occurrence of each of the other types of abnormalities is small, erroneous issuance of the critical alarm can be prevented. It should be noted that issuance of the critical alarm does not always require notification (e.g., a displayed sign or sound) to a user, and may include storage in a storage.

(Second Aspect) In the control device according to the first aspect, the controller may be configured to cause an operation mode of the vacuum pump to transition to an operation limitation mode in which the operation of the vacuum pump is limited as compared to normal operation, in a case where the vacuum pump is restarted after stop in a case where the number of times of occurrence of each of the multiple types of abnormalities exceeds the predetermined threshold.

In the control device according to the second aspect, the operation mode of the vacuum pump transitions to the operation limitation mode when the number of times of occurrence of each of the multiple types of abnormalities occurred in the vacuum pump exceeds the predetermined threshold. That is, based on the number of times of occurrence of each of the multiple types of abnormalities, it is determined whether or not transition to the operation limitation mode is to be made. With this configuration, erroneous transition of the operation mode to the operation limitation mode can be prevented in a case where a probability of the vacuum pump being broken down is low because the number of times of occurrence of only a single type of abnormality is great and the number of times of occurrence of each of the other types of abnormalities is small.

(Third Aspect) In the control device according to the second aspect, the controller may be configured to stop the vacuum pump after the vacuum pump has operated only for a predetermined time after start-up in a case where the operation mode of the vacuum pump is the operation limitation mode. In the control device according to the second aspect, the vacuum pump can be used only for the predetermined time while an operation state of the vacuum pump is checked.

(Fourth Aspect) In the control device according to the second or third aspect, the control device may further include a storage. In this case, the controller may be configured to store a critical alarm issuance history indicating issuance of the critical alarm in the storage in a case where the critical alarm is issued, and determine the operation mode of the vacuum pump as the operation limitation mode in a case where the critical alarm issuance history indicates issuance of the critical alarm when the vacuum pump is restarted. In the control device according to the fourth aspect, issuance of the critical alarm is stored in the storage in a case where the critical alarm is issued so that issuance of the critical alarm before restart of the vacuum pump can be grasped and the vacuum pump can be operated in the operation limitation mode upon restart.

(Fifth Aspect) In the control device according to any one of the second to fourth aspects, the controller may be configured to cancel the operation limitation mode when a dedicated password is input. In the control device according to the fifth aspect, free cancellation of the critical alarm can be prevented, and unnecessary operation of the vacuum pump when a probability of the vacuum pump being broken down is high can be prevented.

(Sixth Aspect) In the control device according to any one of the first to fifth aspects, the predetermined threshold may be changeable. In the control device according to the sixth aspect, a critical alarm issuance condition (a condition for transition to the operation limitation mode) can be set optimally according to use environment of the vacuum pump.

(Seventh Aspect) In the control device according to any one of the first to sixth aspects, the multiple types of abnormalities may include at least two abnormalities selected from an abnormality regarding vibration of the vacuum pump, an abnormality regarding the number of rotations of the rotor, and an abnormality regarding the temperature of the vacuum pump. In the control device according to the seventh aspect, transition to the operation limitation mode (issuance of the critical alarm) can be properly made based on the number of times of occurrence of each of the multiple types of abnormalities leading to breakdown of the vacuum pump. For example, each of the abnormality regarding the vibration of the vacuum pump, the abnormality regarding the number of rotations of the rotor, and the abnormality regarding the temperature of the vacuum pump has a relationship with product accumulation. Thus, in a case where the critical alarm has been issued, it can be assumed that product accumulation is excessive, and overhaul for removing the products is prompted.

(Eighth Aspect) A control method according to an eighth aspect is a control method for a vacuum pump configured to discharge gas by rotating a rotor by a motor. The control method includes counting the number of times of occurrence of each of multiple types of abnormalities occurred in the vacuum pump, and issuing a critical alarm in a case where the number of times of occurrence of each of the multiple types of abnormalities exceeds a predetermined threshold.

In the control method according to the eighth aspect, the critical alarm is issued when the number of times of occurrence of each of the multiple types of abnormalities occurred in the vacuum pump exceeds the predetermined threshold. That is, based on the number of times of occurrence of each of the multiple types of abnormalities, it is determined whether or not the critical alarm is to be issued. With this configuration, in a case where a probability of the vacuum pump being broken down is low because the number of times of occurrence of only a single type of abnormality is large and the number of times of occurrence of each of the other types of abnormalities is small, erroneous issuance of the critical alarm can be prevented.

Various embodiments and modifications have been described above, but the present invention is not limited to the contents of these embodiments and modifications. The embodiments and the modifications may be applied alone or in combination. Other aspects conceivable within the scope of the technical idea of the present invention are also included in the scope of the present invention.

LIST OF REFERENCE SIGNS 1: Vacuum Pump 2: Housing 3: Base 4: Rotor 5: Stator 6: Control Device 7: Operation Device 11: First End Portion 12: Second End Portion 13: Suction Port 14: Base End Portion 16: Exhaust Port 21: Shaft 22: Rotor Blade 23: Rotor Cylindrical Portion 31: Stator Blade 32: Stator Cylindrical Portion 33: Case 41A to 41E: Bearing 42: Motor 42A: Motor Rotor 42B: Motor Stator 43: Rotation Number Sensor 44A to 44C: Displacement Sensor 45: Motor Current Measurement Device 51: Heater 52: Temperature Sensor 53: Heater Current Measurement Device 61: Storage 62: Controller AH: Critical Alarm Issuance History CNT: Abnormality Occurrence Counter CON: Abnormality Occurrence Condition PW: Cancellation Password RCO: Critical Alarm Condition SP1: First Internal Space SP2: Second Internal Space 

What is claimed is:
 1. A control device for a vacuum pump configured to discharge gas by rotating a rotor by a motor, comprising: a controller, wherein the controller is configured to, count the number of times of occurrence of each of multiple types of abnormalities occurred in the vacuum pump, and issue a critical alarm in a case where the number of times of occurrence of each of the multiple types of abnormalities exceeds a predetermined threshold.
 2. The control device according to claim 1, wherein the controller is configured to cause an operation mode of the vacuum pump to transition to an operation limitation mode in which the operation is limited as compared to normal operation, in a case where the vacuum pump is restarted after stop in a case where the number of times of occurrence of each of the multiple types of abnormalities exceeds the predetermined threshold.
 3. The control device according to claim 2, wherein the controller is configured to stop the vacuum pump after the vacuum pump has operated only for a predetermined time after start-up in a case where the operation mode of the vacuum pump is the operation limitation mode.
 4. The control device according to claim 2, further comprising: a storage, wherein the controller is configured to, store a critical alarm issuance history indicating issuance of the critical alarm in the storage in a case where the critical alarm is issued, and determine the operation mode of the vacuum pump as the operation limitation mode in a case where the critical alarm issuance history indicates the issuance of the critical alarm when the vacuum pump is restarted.
 5. The control device according to claim 2, wherein the controller is configured to cancel the operation limitation mode when a dedicated password is input.
 6. The control device according to claim 1, wherein the predetermined threshold is changeable.
 7. The control device according to claim 1, wherein the multiple types of abnormalities include at least two abnormalities selected from an abnormality regarding vibration of the vacuum pump, an abnormality regarding the number of rotations of the rotor, and an abnormality regarding a temperature of the vacuum pump.
 8. A control method for a vacuum pump configured to discharge gas by rotating a rotor by a motor, comprising: counting the number of times of occurrence of each of multiple types of abnormalities occurred in the vacuum pump; and issuing a critical alarm in a case where the number of times of occurrence of each of the multiple types of abnormalities exceeds a predetermined threshold. 